A brain-derived neurotrophic factor (sometimes referred to as “BDNF protein” or merely as “BDNF” herein) is a secretory protein which is known as one of neurotrophic factor families. The secreted BDNF protein is known to bind to receptor tyrosine kinase, TrkB receptor and to be involved in neurogenesis and neural development. Recently, it has been reported that, in patients suffering from depression, the BDNF protein concentration in serum decreases, but that the decreased concentration recovers when an antidepressant takes effect (Non-Patent Document 1). Hence, the substance acting on this factor is expected to successfully improve disease states such as depression.
Plant polyphenols contained in various fruits and vegetables, among others, cacao polyphenols are known to have various physiological activities. For example, it has hitherto been known that procyanidin is a potent inhibitor of amyloid and α-synuclein/NAC fibrillation (Patent Document 1) and that N-phenylpropenoyl amino acid amide suppresses the aggregation of amyloid β-peptides (Patent Document 2). However, none of the documents disclose the involvement of cacao polyphenols in the expression and secretion of BDNF.